SUGAR: the industry’s favorite myths

Researching sugar led me to recognize that some of my core beliefs about nutrition were based on outdated myths. These myths have been thoroughly debunked, yet they remain pervasive in our society and continue to shape the recommendations of health authorities like the USDA and the American Heart Association. 

If you’re interested in understanding how we got ourselves into this silly situation, I recommend you read Gary Taubes’ eye-opening book The Case Against Sugar. In this book, Taubes chronicles the history of human sugar consumption and its scientific study, and he explains how Big Sugar has intentionally muddied our understanding of nutrition to protect their profits. Turns out the sugar industry has been funding research that downplays the harms of sugar since the 1960’s. (For a nice example, see this 2015 NYT article about how Coca-Cola paid researchers millions of dollars to obfuscate the link between soda and obesity.) The sugar industry is also one of the most powerful special interest groups in the United States; it influences legislation via lobbying and political donations, and it is the reason why it took over a decade to get “added sugar” included on nutrition facts labels. It’s also the major reason why the two myths I discuss below won’t die. 

Myth 1 - A calorie is a calorie

You’ve likely heard the phrase “a calorie is a calorie” or “calories in, calories out” used to express the idea that it’s the number of calories, not the type of food, that matters when it comes to our weight. It’s a central tenet of diet culture. But the truth is that different food molecules have different effects on our bodies, and that fructose (which is only found in sweet foods) has the nastiest of effects. (See my last post to read up on these effects.)  

In her book Glucose Revolution, Jessie Inchauspé cites a 2015 study led by endocrinologist Robert Lustig as a compelling illustration of this point. In this study, obese kids/teens were put on a diet in which added sugar (which comprises glucose and fructose) was replaced with starch (which comprises only glucose), e.g., donuts were swapped out for bagels. The study diets were carefully designed so that the kids were eating the same number of calories and carbs as they had been, just far less added sugar. The researchers reported that, in just 9 days, this sugar>starch swap increased satiety and improved virtually all measures of metabolic health (e.g., blood pressure, triglyceride levels) without changing weight. These results clearly demonstrate that calories from fructose are more harmful than calories from glucose, and that the negative effects of sugar go far beyond the “empty calories” that it provides. 

One key takeaway here is that cutting calories indiscriminately is a bad approach for losing weight. When we cut calories but are still eating in a manner that spikes our blood glucose, we make things needlessly difficult for ourselves because (1) the blood glucose rollercoaster makes us feel hungry all the time, and (2) the amount of time our bodies spend in fat-burning mode is limited by the extended presence of insulin in our blood. Thus, being mindful of sugar rather than calories makes weight loss efforts both more effective and less painful. 

Myth 2 - Fat makes us sick

Doctors have been blaming dietary fat for heart disease (and diabetes, and obesity) since the 1950’s, when rockstar physiologist Ancel Keys proposed the “diet-heart hypothesis,” which suggests that saturated fat causes heart disease by raising blood cholesterol and thereby causing plaque to build up in arteries. This hypothesis became dogma as a result of Key’s aggressive personality, the influence of the American Heart Association (who quickly adopted it), and the sticky dollars of Big Sugar.

Some particularly blatant evidence of Big Sugar’s involvement in advancing this hypothesis was published in a 2016 JAMA Internal Medicine paper. Using internal industry documents found buried in the Harvard archives, the authors of this paper revealed that, in 1967, the sugar industry paid three Harvard scientists to review a collection of handpicked studies with the explicit aim of refuting the growing evidence linking sugar to heart disease and shifting the blame to saturated fat. This paper is nicely summarized in a 2016 NYT article, which highlights the fact that one of these scientists (Frederick J. Stare) was the chairman of Harvard’s nutrition department, while another (D. Mark Hegstead) would later become the head of nutrition at the USDA. These prominent men and their sugar-daddy-funded review would influence the scientific discourse for years to come. 

The sad truth is that the diet-heart hypothesis was built on shitty (i.e., weak, associational) evidence. As is neatly documented in this 2022 opinion piece, randomized clinical trials (i.e., the gold standard of evidence) have provided very little support for it. While some trials have detected a small reduction in disease with a low saturated fat diet, most show no effect, and a couple even show a negative effect. These clinical trials have been analyzed en masse in over 20 scientific reviews, which have largely concluded that saturated fats have no effect on cardiovascular outcomes. 

Yet, despite the dearth of evidence, the diet-heart hypothesis has shaped dietary guidelines ever since its inception. In the 80s/90s, these guidelines spawned a low-fat diet craze in the US in which throngs of Americans put their faith in newfangled low-fat foods only to get fatter and sicker than ever. The problem with low-fat foods is that they are typically loaded up with sugar to compensate for the lack of fat. (Fat enhances flavors and gives foods a pleasurable mouthfeel, and a lot of foods really suck without it.) In contrast to fat, which takes a long time to digest and makes us feel full and satisfied, sugar is rapidly absorbed and can make us feel even hungrier. Thus, swapping fat for sugar, as the low-fat dieters did, is a perfect recipe for metabolic syndrome.

Conclusion

It’s in the sugar industry's best interest to keep us focused on calories and fat and distracted from the ever-growing body of evidence that implicates sugar in disease. But if we really care about our health, we need to dismantle the false beliefs that they’ve instilled in us and start recognizing their cash cow as the harmful substance it is.